Device for securing artificial bicuspids or molars in crown and bridge work.



' PATENTED SEPT. 27, 1904.

J. R. MITCHELL.

DEVICE FOR SECURING ARTIFICIAL BICITSPIDS 0R MOLARS IN GROWN AND BRIDGE WORK.

APPLICATION FILED JULY 8, 1903.

NO MODEL.

g R/Z YIMML UNITED STATES Patented September 2'7, 1904.

PATENT rEicE.

JOHN ROBERT MITCHELL, OF PERTH, CANADA.

DEVICE FOR SECURING ARTIFICIAL BICUSPIDS OR MOLARS IN CROWN AND BRIDGE WORK.

SPECIFICATION forming part of Letters Patent No. 770,768, dated September 27, 1904.

Application filed July 8, 1903. Serial No. 164,723. (No model.)

T0 at whom, it may concern.-

Be it known that I, JOHN ROBERT MI'roHELL, of Perth, in the county of Lanark, in the Province of Ontario and Dominion of Canada, have invented certain new and useful Improvements in Devices for Securing Artificial Bicuspids or Molars in Crown and Bridge Work; and I do hereby declare that the following isa full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part hereof.

My invention, which will be hereinafter fully set forth and claimed, relates to artificial teeth, and particularly to devices for securing bicuspids and molars in plate, crown, and bridge work.

The object of my invention is to obtain a firmer support and more secure hold for the porcelain or other artificial bicuspids and molars, avoid heating the porcelain during construction, and at the same time expose less of their settings to view.

Figure 1 is an enlarged rear View of a bicuspid-facing formed according to my invention. Fig. 2 is a vertical section of the same set in a gold backing. Fig. 3 is a side view of the porcelain and backing. Fig. 4 is a face view of the same. Fig; 5 is a front view of the same, and Fig. 6 shows it connected as or part of a bridge.

A represents an artificial-bicuspid facing, usually porcelain. The rear part at the base end is set back to form a substantial shoulder a. A mortise or pin-hole is sunk in the face of the shoulder and lined with metal, usually platinum, which lining a is baked into the porcelain. This mortise is placed close to the hollow angle of the shoulder, being approximately near the center of the tooth. A backing B is formed to surround the porcelain all round except the front and face, but comes just around the point at 2 and around the rear part of the face at 3. This backing, the interior of which naturally has the counterpart of the shoulder a, is provided with a tenon or pin 5, adapted to engage the lined mortise or pin-hole a snugly. Before being finally put together all the contact-surfaces are covered with cement and a tight joint is obtained.

The backing may be soldered at each side to adjoining cups or backings A and 5, which form part of a bridge, as shown in Fig. 6, or in any other suitable manner.

It will be seen that this method of setting forms a solid seat for the porcelain or other facing, shows a minimum extent of gold on the front, and dispenses with the usual cup in bridgework, which cup is hard to make and which is replaced by a backing, such as B, which may bereadily burnished on. The pin-hole or mortise a being lined also permits of being made smaller to fit a smaller pin or tenon, and thus, especially in bicuspids, allows more substance at the base of the porcelain around. said mortise for fitting and grinding.

I claim as my invention 1. An artificial bicuspid or molar having at its rear a set-off to form a shoulder with a mortise or pin-hole sunk in the face of said shoulder and a metallic lining to said mortise baked into the substance of the tooth, substantially as set forth.

2. A backing for abicuspid or molar formed with a set-off shoulder to fit a similar shoulder on the artificial facing and surrounding the latter completely except on the front and face but covering the adjoining edges of said parts and provided on the face of said shoulder with a pin or tenon adapted to engage a mortise in said artificial facing, substantially as set forth.

3. The combination of an artificial bicuspid or molar having at the rear a shoulder formed' by a set-off at the base, a metallic lining for a mortise or pin-hole sunk in the base of said shoulder, a backing surrounding the porcelain all round except its front and face but tipping the adjoining edges of the same and provided with a tenon or pin adapted to engage said mortise in the shoulder, substantially as set forth.

In testimony whereof I have signed in the presence of the undersigned witnesses.

JOHN ROBERT MITCHELL. Witnesses:

A. HARVEY, G. PIOTRZKOWSKY. 

